Unable to connect to the Radio

Hello!
On a Pixhawk 6c, we have a Radiomaster ER6 ELRS receiver, which outputs to the CSRF/SBUS channel on a telem1 port. We are unable to start radio calibration. It seems that the remote is connected to the receiver, but the Pixhawk is not reading the signals.

Did anyone have a problem similar to ours? Do you have any suggestions?

Thank you!

What Firmware version are you using?